sorry, can't help with dating, but just to say that if we buy something that is reputed to be Georgian, then it's quite legitimate for the piece to be anything from 1714 to 1830 - the final few years being what collectors call Regency. It should be easy to tell if the glass posted here is lead glass - there should be a good ring to the glass - the colour is often leaden, but that's not essential, apparently.
The piece quoted as William IV would be c. 1830 - 1837, not c. 1820 - no idea why the poor guy didn't last very long. Nice glass by the way.
